BATOCRINID &. 3 521 
sible they may have to be separated subgenerically, perhaps under 
Pradocrinus. 
The anus of Periechocrinus is rarely observed, and throws no light on the 
relations of the genus. P. moniliformis was probably provided with a short 
anal tube, while most of the other species seem to have had a mere 
protuberance. 
Pradocrinus de Verneuil (1850) is possibly identical with Periechocrinus, 
and also Geocrinus d’ Orbigny, which was proposed in the same year. Johannes 
Miiller referred Pradocrinus to Pyaidoerinus, under which he proposed to em- 
brace all Actinocrinidse possessing interdistichals. Angelin identified Zrocho- 
crinites Pander with Periechocrinus ; while Bigsby took it to be a synonym of 
Glyptocrinus. The name Trochocrinites was preoccupied by Portlock in 1848, 
but 7’. levis, the only species referred to it, was described from an imperfect 
specimen, and its relations cannot be accurately determined. Hall's Actino- 
erimus semiradiatus, which is known only from natural casts, and which we 
formerly referred to Periechocrinus, is possibly a Macrostylocrinus. 5S. A. Mil- 
ler’s Saccocrinus Gorbyt, from Decatur Co., Ind., is described from a cast, and 
it is doubtful if it belongs to this genus. | 
Periechocrinus speciosus (H41z). 
Plate L. Figs. 6a, 0. 
1862. Saccocrinus speciosus —Haut; Paleont. N. York, Vol. II, p. 205, Plate 46, Figs. 1, 2. 
1881. Periechocrinus speciosus—W. and Sp.; Revision Paleocr., Part IL., p. 133. 
Rather large. Calyx elongate; sides but little convex ; greatest width 
across the first distichals; plates smooth, even without the usual radial 
ridges. 
Basal cup very deep. Radials and costals once and a half as long as wide. 
decreasing in size in ascending order, their upper and lower faces exceed- 
ingly narrow, the upper sloping faces of the radials unusually short. Dis- 
tichals four; the first about half the size of the first costals; the second 
much smaller; the upper ones, which are followed by free arm plates, short 
and quadrangular. Arms branching a little above the calyx, and twice again 
higher up; they are proportionally thin and taper gradually to the tips. 
Interbrachials rather large; the first followed by five or six ranges of two 
plates each. Interdistichals in three or four rows. Construction of the anal 
side not known, nor the structure of the tegmen. Column round; the nodal 
joints slightly projecting; their edges covered with a row of small nodes, 
66 
